You're probably already aware that it's hard to change someone's mind with logical arguments and evidence, especially about emotionally charged topics. But are there exceptions?

David McRaney, bestselling author of "You Are Not So Smart" (and host of the blog and podcast by the same name) describes his experiences with people who have done an about-face on some important topic, like 9/11 conspiracy theories. He and Julia discuss a technique for changing someone's mind with evidence, how individual mind-change mirrors scientific progress, and what happens when you confront Trump fans with facts that contradict their narrative.

Reader Comments (34)

If you re-listen to your interview, you may realize that you are stretching the meaning of "evidence". Lack of evidence of something happening is not equal to evidence that something didn't happen. Not all people are conspiracy theorists just because they don't trust a statement that an event did not happen just because video footage of that event was never found.

"If you re-listen to your interview, you may realize that you are stretching the meaning of "evidence". Lack of evidence of something happening is not equal to evidence that something didn't happen. Not all people are conspiracy theorists just because they don't trust a statement that an event did not happen just because video footage of that event was never found." If there is no evidence of something happening why do you believe it happened? I would suggest that lack of evidence of an event is in support of evidence it did indeed happen. If you could explain to me how I am missing a piece of evidence, please do :)

"If there is no evidence of something happening why do you believe it happened? I would suggest that lack of evidence of an event is in support of evidence it did indeed happen. If you could explain to me how I am missing a piece of evidence, please do :)"

If there is no evidence of something happening, you wouldn't believe it happened. However, you would not call the lack of evidence "evidence" that something didn't happen. It seems more logical to say "We found no evidence that the event happened" rather than "We found evidence that the event didn't happen".

evidence?: in some circumstances a lack of evidence can also double as evidence against an idea. Suppose that we look for ten thousand years and spend millions of dollars to find unicorns in the forest and cannot find any signs of their presence. At the end of the ten thousand years, we have more reason to disbelieve in unicorns than we did at the beginning of our search. Does that make sense?

Evidence? "however, you would not call the lack of evidence "evidence" that something didn't happen." depending on the circumstances you very well might. Let us explore the claim as made by Mr. Trump, that people were dancing in the street after the World Trade Centre Attacks, it was 2001 do you not think that Al Qaeda would not have filmed that and used it and released it to further demorilise the west, or that a passer by would not have caught it on camera phone? That local intelligence agencies would not have reported it and the Bush Administration used it in support of their war effort? Not one piece of evidence exists and in the modern age after an event that large that is very much evidence it never took place, we live in the age of instant media, of images reaching our screens moments after they happen, which means that one side or the other, or some private citizen would have benefited from that footage and it would be all over youtube by now, so yeah I am calling it evidence it never took place

I figured that Trump conflated the famous CNN/Reuters footage of Palestinians celebrating 9/11 in Jerusalem with reports of Muslims celebrating in New Jersey, but no, "he's just straight up lying about it," while Brian Williams and Hillary Clinton were just victims of the False Memory Syndrome producing false memories of being shot down over Iraq and landing under sniper fire in Bosnia.

When your guest was discussing Trump’s “lie” about Muslims celebrating after 911 it seems that he was applying motives to Trump that may or may have not been there based on his own bias.

Could it not be that Trump was simply wrong or mistaken?

How did he determine that it was a fact that Trump was consciously lying?

Maybe he gives Trump more credit than he is due. In fact, one could argue based on Trump’s record that it is far more likely that he was wrong than he was lying, or at least just as likely.

The fact that news organizations did not believe it was true does not mean that Trump did not believe it was true.

Since the questions he was asking the Trump rally attendees may have been based on a supposed or false premise, how valid were their responses in terms of gaining insight to how people change their minds when presented with contradictory “facts”?

If you replace “are wrong” with “lie” in the response that all politicians sometimes lie, it makes their responses seem reasonable instead of dismissive.

Perhaps this is a reminder that thinking critically is a constant battle for all of us, even when researching how to think critically.

Am I wrong, or is there a GIGANTIC omission in this episode? The paper that famously found great results from the door-to-door canvassing technique was a huge fraud story and the paper was retracted! How was this not brought up? Julia even jokes that she'd think it was fraudulent if the claimed efficacy was, say, 80%, and somehow that didn't prompt a discussion about the fraud surrounding this research? The fraud that was a huge news story last year?

Note that the technique may well be legitimate, but to talk about glowing results without discussing the fraud angle - even as a footnote at the end or in the description - seems like a huge oversight.

I just want to clarify that David *did* acknowledge to me that the original study from the Leadership Lab had been found to be fraudulent (but told me off the record that new research was coming out this week vindicating the technique). I cut the section about fraud partly because we were way over time, and also because I didn't want to include the part about fraud without the part about the embargoed new research. But I still felt comfortable leaving in the Leadership Lab section since I knew the new research was coming out shortly after the episode.

In retrospect, maybe I should've saved this episode for the following week, though! I hadn't thought ahead about listeners investigating the LL in the period of a few days between the episode's release and the new research embargo being lifted.

The new research won't turn out to be fraudulent?In any case, couldn't the technique work both ways, for example introducing people to conspiracy theories by showing them that they've been accepting the official story without questioning it?I suppose cults and missionaries are good at brainwashing people too.

I also was a little put off by the unpleasant tone used to discuss Trump supporters. While I disagree with almost everything Trump advocates, one of the things I really enjoy about Julia and Rationally Speaking is the civility and thoughtfulness of the show.

Haha, your own definition of evidence gives an example, "the study finds little evidence of overt discrimination." That doesn't count as evidence that there's no overt discrimination?If there's no evidence because nobody looked for it, then that's not evidence of absence, but if people looked hard and failed to find evidence, then that IS evidence of absence. If I can't find my keys in my pocket, that's evidence that they're not in my pocket.

The lack of evidence can be indeed evidence if there is high likelihood that the evidence would be found if it existed. For instance, not finding an elephant in my bathroom is certainly evidence that there is no elephant in my bathroom.

Max and Greg. I didn't define "evidence", rather I am trying to point out it's missuse by so many here. What both of you have pointed out is a lack of evidence, not evidence. There is a difference in meaning. What David and you all are talking about is "a lack of or little evidence that something occurred " Why not just say that? What is so hard about conceding the word "evidence" was used improperly in this context? It absolutely does not change the outcome of the argument being made. Does it? Evidence = something found. Lack of evidence = nothing found. You found no keys in your pocket or no elephant in your bathroom only means you have no evidence of keys in your pocket or elephant in your bathroom. What you do have evidence of is an empty pocket and an empty bathroom...because they are empty, not because they are empty of keys or empty of elephants.

The bathroom isn't completely empty. It has a toilet and a sink and stuff. The evidence points to the bathroom being specifically empty of elephants and other large animals.The definition that you yourself cited ("your own definition" for short) just says that evidence is the "available body of facts or information indicating whether a belief or proposition is true or valid." The observation that there's no elephant in the bathroom indicates that there's no elephant in the bathroom.Saying "a lack of evidence" is vague because it doesn't tell you whether or not anyone bothered to look.

Regarding the people at the Trump rally, I was thinking that the following point should hopefully be taken as read, but it wasn't said in so many words. Consider yourself in the position of the rally-goer, supposing it to be a candidate that you like and think would be a good president, perhaps Bernie Sanders, or John B. Anderson, or Screaming Lord Sutch, according to your preferences. Someone approaches you and asks you about an inaccuracy X said by your candidate ... even his best friend and his mother admit that X is not true! Wouldn't it be rational at this point to first consider whether your support for the candidate hinges on the accuracy of X? And if it doesn't, if you feel like X is not all that important and you would still support Sanders or Lord Sutch or whoever regardless, then would you really feel like hashing it out right then and there regardless, with a stranger? Ought you to? Why bother?

Or consider a more extreme example. What if you are the candidate, and you're at a debate. Now, if you are a person who cares about being honest, then hopefully whatever X you've said in the past is correct. But, guess what, even if it happens that you were wrong about something, the debate is not the right time and place to give a completely sober and frank assessment of the matter. You don't have to keep insisting that it's true if it's not, but you certainly might want to change the subject and talk about something else. You have a job to do, which is convincing people to vote for you.

From this perspective, I guess the question is, when is the time and place and with whom are you going to really assess whether your opinions are correct or not? Or is it always a debate all the time? If so, then you'll never feel like it's time to reconsider your opinions.

I too find it interesting that the guest chose to visit a place where there was no realistic expectation that he could change someone’s mind in order to study why it is difficult to change someone’s mind. Or maybe that was the point.

Aren’t this podcast and this study (book?) supposed to be about critical thinking? Isn’t referencing Fox and CNN to prove a point a logical fallacy? Isn’t it using an appeal to authority to establish a “fact”?

It appears that he wasn’t trying to change their minds about whether or not Muslims celebrated, but he was trying to change their minds about supporting Trump. As if that single point should be a game changer for them.

It could be that some people support Trump because they prefer him to the available alternatives in spite of his shortcomings. Maybe to them he is the cleanest dirty shirt.

Perhaps it would be a good idea to present people with a situation where they are more likely to change their minds, like a math problem or a memory test, and see what level of evidence is required for them to change their mind about something that they clearly and measurably got wrong, something less emotional and complex than politics.

I'm a listener from outside the US who is horrified by the idea of Donald Trump as a presidential candidate and have difficulty imagining why anyone would want to vote for him - and yet I too was disappointed by the ridiculing of Trump and his supporters at several points during this conversation. That doesn't seem to be a good way to start to change anyone's mind. I agree with the commenter above that Trump's belief that he saw people in New Jersey celebrating after 9/11 seems more likely to be a genuine mistake than Hillary Clinton's belief that she came under sniper fire in Bosnia (though perhaps it makes a difference that Clinton apologised when she was corrected, whereas Trump has not).

However, the substantive content of the conversation was really interesting, and I'm looking forward to reading David McRaney's book when it's available.